A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
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A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
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A Fresh Look at Marine Magnetic Anomalies, One of the Key Datasets in the Development of Plate Tectonics by Ian Norton - 2014 PaleoGIS & PaleoClimate Users Conference
- 1. A fresh look at marine magnetic anomalies, one of the key datasets in the development of plate tectonics. Ian Norton, Larry Lawver, Lisa Gahagan Institute for Geophysics University of Texas at Austin From Vine and Matthews, 1963: Calculated with reversals Observed Calculated with constant magnetization Sandwell gravity
- 2. The EDSAC-2 computer used by Vine & Matthews http://en.wikipedia.org/wiki/EDSAC_2 EDSAC = Electronic Delay Storage Automatic Calculator
- 3. PLATES Database • Plate model • Database: oceanic magnetic and tectonic (plate boundaries, paleomagnetic, hot spots, geological and geophysical data to extend the span and accuracy of global plate reconstructions) • This talk: a look at magnetic anomalies. Crust Code
- 4. Data from Global Magnetics Database http://www.soest.hawaii.edu/PT/GSFML/ML/index.html Green – Cande & Stock, 2004 Black – Granot et al., 2013 Australia Database run by Paul Wessel (Hawaii) & Dietmar Müller (Sydney) Antarctica -40 -50 -60 100 140
- 5. Data from Global Magnetics Database http://www.soest.hawaii.edu/PT/GSFML/ML/index.html 115˚E 120˚E 60˚S Mismatches 5-6 km to as much as 35 km • Great dataset, needs work to use Green – Cande & Stock, 2004 Black – Granot et al., 2013
- 6. Example magnetic profile from Mascarene Basin Base: Sandwell free air gravity 23.1
- 7. Example magnetic profile from Mascarene Basin • VGG emphasizes fracture zones and extinct ridges Base: Sandwell vertical gravity gradient 23.1
- 8. ModMag model of Mascarene Basin profile • Really good match between synthetic and observed • Easy to map details of age interpretation Young end at max +ve, old end at max -ve ModMag: Matlab program by Mendel, Munschy & Sauter, 2005. This profile is from example data files that are included with download. Computers & Geosciences, Volume 31, Issue 5, June 2005, Pages 589–597
- 9. ModMag GUI
- 10. Entry in magnetic anomaly database Base: Sandwell free air gravity 23.1
- 11. M-anomalies in the Mozambique Basin Data from König and Jokat, 2010
- 12. M-anomalies in the Mozambique Basin Data from König and Jokat, 2010
- 13. Line SO183-11 from Mozambique Basin • Good match over parts of profile • Need multiple lines for regional identifications • Mapping of young-old edges of anomalies not quite so accurate Data from König and Jokat, 2010 Young end close to max –ve, old end close to max +ve
- 14. Greenland motion: Plates project database
- 15. Overlap between Greenland and Barents – Svalbard margin Overlap
- 16. Overlap between Greenland and Barents – Svalbard margin Next slide
- 17. Overlap between Greenland and Barents – Svalbard margin 120-130 km
- 18. Point path visualization, Greenland relative to Europe Gaina et al. (2009) poles 100 km
- 19. The Svalbard Margin – Paleocene-Eocene foldbelt followed by some rifting (age?) Leever et al. 2011 after Faleide et al. 2008 Leever et al. 2011 after FG = Forlandsundet Graben Bergh et al., 1997 and Braathen et al. 1999
- 20. Stylized present-day G E Reconstructions should show (in sequence) transpression to transtension to oblique divergence with spreading Stylized 33 Ma (e.g. Engen et al. 2008) G E Stylized Oligocene (overlap to account for transtension) G E Stylized Paleocene (gap to account for transpression) G E Present-day 47 Ma Should show a gap at 47 Ma, not overlap
- 21. 120-130 km overlap 47 Ma reconstruction Europe fixed, Gaina et al. 2009 poles
- 22. 47 Ma reconstruction – can Greenland be shifted to avoid overlap with Svalbard? • Check magnetic lineation identifications in Labrador Sea
- 23. Labrador Sea magnetic data Data from http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=8127
- 24. Labrador Sea magnetic data – modeled profile Data from http://gdr.agg.nrcan.gc.ca/gdrdap/dap/index-eng.php?dapid=8127
- 25. Labrador Sea Vertical Gravity Gradient – shows extinct ridge Sandwell 2014
- 26. Extract topography/bathymetry Sandwell topography
- 27. Extract sediment fill http://www.ngdc.noaa.gov/mgg/sedthick/index.html
- 28. Get basement depth km Meters Extinct ridge
- 29. ModMag model • This version provides a reasonable match
- 30. This is the currently accepted interpretation • These essentially sinusoidal anomalies are hard to identify with certainty, need regional context to settle on interpretation This area not modeled
- 31. Magnetic anomalies around N Atlantic triple junction Maus et al. 2008 magnetics
- 32. 120-130 km overlap 47 Ma reconstruction Europe fixed, Gaina et al. 2009 poles
- 33. 47 Ma reconstruction – can Greenland be shifted to avoid overlap with Svalbard? • Labrador Sea identifications not definitive • Triple junction provides strong constraint – can’t move Greenland • How to fix the overlap? Hopefully PhD student Bereke Karainov at UiS can figure it out! Triple junction
- 34. It’s all in the stripes…
Editor's Notes
- König and Jokat, 2011 Advanced insights into magmatism and volcanism of the Mozambique Ridge and Mozambique Basin in the view of new potential field data. Geophys. J. Int. (2010) 180, 158–180 doi: 10.1111/j.1365-246X.2009.04433.x
- König and Jokat, 2011 Advanced insights into magmatism and volcanism of the Mozambique Ridge and Mozambique Basin in the view of new potential field data. Geophys. J. Int. (2010) 180, 158–180 doi: 10.1111/j.1365-246X.2009.04433.x
- Figure 2. Cross sections. (a) Crustal structure across the Svalbard Margin, no vertical exaggeration (modified from Faleide et al. [2008]). I, thinned continental crust; II, crust thickened during Tertiary; III, crustal thickness unaffected by Tertiary tectonics. Stipples, sediments; hatching, oceanic crust. Location in Figure 1. (b) Generalized cross section of the WSFTB in Oskar II land (modified from Bergh et al. [1997] (AAPG©1997 reprinted by permis ion of the AAPG whose permission is required for further use) and Braathen et al. [1999b]). The WSFTB is divided into four zones of different structural style. The western Hinterland zone and the basement‐involved fold‐and‐thrust complex correspond to crustal zones and II, respectively (see Figure 2a). D, Devonian; Ca, Carboniferous; Cp, Carboniferous‐Permian; hatching, Permian evaporites; Tr, Triassic; JC, Jurassic‐Cretaceous; T, Tertiary. FG, Forlandsundet Graben; SEDL, Svartfjella‐Eidembukta‐Daudmannsodden lineament [Maher et al., 1997]; BFZ, Billefjorden fault zone; LFZ, Lomfjorden fault zone. Location in Figure 1. SFZ, Senja Fracture Zone; VVP, Vestbakken Volcanic province; NGS, Norwegian‐Greenland Sea; HFFZ, Harder Fjord Fault Zone; TLFZ, Trolle Land Fault Zone. (b) Simplified tectonic map of Spitsbergen showing the four main zones of the WSFTB. Bold gray lines indicate locations of cross sections in Figure 2. BH, Brøggerhalvøya; OL, Oscar II Land; NL, Nordenskiöld Land; FG, Forlandsundet Graben; SEDL, Svartfjella‐Eidembukta‐Daudmannsodden Lineament; BG, Bellsund Graben; IYF, Isfjorden‐Ymerbukta fault; COB, continent‐ocean boundary.